A number of exhaust purifiers have been developed which rely upon catalytic oxidation to remove impurities from the exhaust fumes of internal combustion engines. The present invention facilitates the efficient removal and replacement of used catalytic particles from these purifiers, resulting in ease of maintaining operating efficiency of this type of pollution control device.
Generally, catalytic exhaust systems require the provision of a large, catalytic surface area over which hot exhaust gases may pass. One common method of providing such a surface area is to provide a bed of discrete catalytic particles each of which has a surface coating of precious metal based catalytic material.
The active catalyst materials presently in use are rare and expensive, and it is impractical to provide a large enough supply of catalytic particles to compensate for natural attrition over an unlimited period of time. Also, the catalytic material can become poisoned and inactive due to contamination from various sources including the lead contained in the gasoline. For these reasons, numerous systems have been devised to rejuvenate catalyst particles which have become degraded or inactive.
Patent application Ser. No. 240,969 entitled "Method and Apparatus for Exchanging Catalyst in a Catalytic Converter". owned by the assignee of the present invention, provides a system for emptying and refilling the catalytic particle bed of a horizontal-bed purifier. Further, U.S. Pat. Nos. 3,181,291 and 3,295,565, assigned to the assignee hereof, show vacuum systems for removing and replacing catalytic particles.
Prior catalyst changing systems have often employed a suction wand for the removal of particles from the catalyst bed. These systems require access to the end of the purifier housing, which is normally mounted in a position directly under the "floor boards" of the automobile. Access to these purifiers is normally available because horizontal-bed catalytic exhaust purifiers require a mounting position providing substantial road clearance. This clearance is necessitated by the thickness which results from the requirement that the intake and exhaust ports be vertically displaced by a distance greater than the thickness of the particle bed area.
The more recent sloped-bed design reduces the total under-floor clearance required while increasing the effective surface area of the catalyst bed. It generally takes the shape of a flat rectangular box formed of top and bottom halves which are joined with a protruding longitudinal flange. Intake and exhaust ports are provided usually at either end of the housing. The inclined catalytic bed is usually formed by grids which connect to the housing above the intake port at one end and below the exhaust port at the other end. This diagonal arrangement of the catalytic bed provides an increased catalytic surface area over which the exhaust gases must pass.
In some models, such as those represented in the drawings herein, the intake and exhaust ends of the purifier are rounded or diagonally truncated to reduce the space required for installation and to facilitate more efficient gas flow through the purifier. One of the most popular of these truncated purifiers is octagonally shaped, two sides being elongated to increase the distance between the intake and exhaust ports, and the two sides in which the ports are formed being abbreviated to the approximate diameter of the pipes to which they are connected. While this is the general form, the shape may vary depending upon the type and size of automobile to be facilitated.
In order to achieve the design advantages described above, sloped-bed catalytic purifiers possess certain inherent structural disadvantages. Unlike previous cylindrical purifiers, the fill hole in a sloped-bed catalytic purifier cannot conveniently be placed on any vertical side of the purifier due to the thickness of the purifier housing and the characteristic longitudinal flange which contributes to the purifier's durability. Consequently, the most popular location for the fill hole is on the bottom surface of the purifier at its intersection with the particle bed. This presents an unusual difficulty in exchanging the catalytic particles, since the exchange procedure must be performed while the purifier is mounted on the automobile; the purifier cannot be inverted for a gravity fill, as might be accomplished during manufacture. One reason for this is that there is a danger of attrition in particles which are not fully compacted in the converter, which might happen if the converter is pulled off the vehicle and the catalyst changed on the bench. Also, another reason for not removing the converter from the vehicle is to maintain the integrity of factory connections which prevent poisonous carbon monoxide from leaking into the passenger compartment.
While gravity alone might be suggested to empty contaminated particles, field conditions demonstrate that this is not feasible due to exhaust residues which coincidentally build up in the particle bed and which cause contaminated particles to clump and otherwise lodge against the particle bed grids. Furthermore, the elongation and reduction in width of the purifier results in slightly inclined particle beds which encourage particles to lodge in the narrow recesses thereof. For all of these reasons, it is very difficult to dislodge and to remove catalytic particles from a converter which has been used for an extended period of time.
An object of the present invention is to provide a clampable vibrator for use in a system for emptying and refilling the fixed catalytic bed of a catalytic exhaust purifier.
Another object of the invention is to provide a self-supporting catalyst changer which may be used to change the catalyst in a motor vehicle with ease and efficiency.
Another object of the invention is to provide a quick and thorough means for removing catalyst particles from the catalytic exhaust purifier and for refilling with fresh particles and compacting the fresh particles.
Another object of the invention is to provide a device which facilitates gentle handling of the catalytic particles during the exchange process.
Still another object of the invention is to provide substantially complete emptying of a catalyst bed under conditions of extreme contamination, and to facilitate refilling the bed so that replacement particles substantially completely occupy the particle bed area in a tightly packed configuration.
Yet another object of the invention is to provide a device which is self-contained and can be stored conveniently in one piece, which is economical, compact, quiet, clean, non-clogging, rugged and flexible enough to handle various types of catalytic purifiers, and suitable for use in facilities equipped with nothing more than standard "gas station" equipment.